O, o-dialkyl s-(tetrahydro-2-pyranyl) phosphorothiolothionates



United States Patent-O 0,0-DIALKYL S-(TETRAHYDRO-Z-PYRANYL) PHOSPHOROTHIOLO'IHIONATES No Drawing. Filed Dec. 6, 1957, Ser. No. 700,978

6 Claims. (Cl. 260-3453) This invention relates to new organophosphorus compounds and to a method for their preparation. In a specific aspect, this invention relates to new phosphorothiolothionates and to a method for their preparation.

Many organophosphorus compounds have been found useful in recent years as insecticides, plasticizers as well as a variety of other uses. Accordingly, it is an object of this invention to provide new organophosphorus compounds that have outstanding insecticidal activity, partioularly against mites and aphids. It is another object of this invention to provide a novel method for preparing these new organophosphorus compounds. The out standing utility of these compounds as insecticides is particularly unexpected when it is realized that closely related compounds having a similar structural formula possess little, if any, insecticidal activity at the concentrations at which these new compounds are eminently toxic against mites and aphids.

In accordance with this invention we have prepared new organophosphorus compounds having the structural formula:

(Bonus s n wherein R is as defined above with a substituted dihydropyran having the structural formula:

wherein R R R R and R are as defined above.

The reaction forming the compounds of this invention is usually carried out by slowly adding one of the re actants to the other reactant and any mode of addition of the reactants can be employed. The reaction is ordinarily carried out at a temperature within the range of 25 to 150 C., preferably within the range of 25 to 100 C. The molar ratio of reactants can be varied rather widely, but it is preferable to employ equal molar quantities of the reactants for the most desirable results.

It is possible to conduct the reaction in theabseuce of r 2,972,621 Patented Feb. 21, 1961 "ice any solvent medium, but if a solvent is employed, normally liquid hydrocarbons and their halogenated derivatives can be used. Suitable solvents are normally liquid aliphatic and aromatic hydrocarbons such as pentane, 5 hexane, heptane, octane, benzene, toluene, xylene, and the chlorinated derivatives of these hydrocarbons. The reaction can be conducted in the absence of any catalyst, but if a catalyst is desired for the reaction, basic catalysts such as tertiary amines, and in particular trialkyl amines such as triethyl amine, are quite suitable. The period for reaction generally varies from about to 8 hours.

The dihydropyrans that are employed to produce the compounds of this invention can be readily prepared by the reaction of an alkenyl ether with an u,p-unsaturated aldehyde or ketone such as acrolein and crotonaldehyde. A specific procedure for producing the dihydropyrans is disclosed by Longley et al. in JACS 72, 3079 (1950).

The compoundsof this invention and their preparation, as well as their utility, are described in the following examples:

EXAMPLE 1 0,0-diethyl S-(6-eth0xytetrahydro-Z-pyranyl) phosphorothiolothionate Diethyl phosphorothiolothionate (0.1 mole) was placed in a flask and stirred while 2-ethoxy-3,4-dihydro- ZH-pyran (0.1 mole) was added dropwise. The reaction is exothermic, and the temperature of the reaction mix- 5 ture rose to 65 C. About 15 minutes were required to add the 2-ethoxy-3,4-dihydro-2H-pyran. After the temperature of the reaction mixture had dropped to 25 C.,

it was heated on the steam bath with stirring for 15 minutes. The product was then stripped under reduced pressure (1-2 mm.) to remove volatile impurities. The

This compound was prepared from diethyl phosphorothiolothionate (0.1 mole) and 2-rnethoxy-4-methyl-3,4-

dihydro-2H-pyran (0.1 mole) according to the procedure of Example 1, n 1.5120.

EXAMPLE 3 0,0-diethyl S-(6-eth0xy-4,5,5-trimethyltetrahydro-Z- pyranyl) phosphorothiolothionate H CH3 CH3 CHa o.n,o ,1 s s 00.155

This compound was prepared from 2-ethoxy-3,3,4-trimethyl-3,4-dihydro-2H-pyran (0.1 mole) and diethyl phosphorothiolothionate (0.1 mole) according to the procedure of Example 1.

3 EXAMPLE 4 0,0-dimethyl S-(6-eth0xy-5,5-dimethyltetrahydro-Z- pyranyl) phosphorothiolothionaze CH3 10H. (CHaO)2P (S) S-Ao \H H OCzHs,

This compound was prepared from dimethyl phosphorothiolothionate (0.1 mole) and 2-ethoxy-3,3-dimethyl-3,4-dihydro-2H-pyran (0.1 mole) according to the procedure of Example 1.

EXAMPLE 5 0,0-diispr0pyl S-(6-meth0xy-3-methyltetrahydro-Z- pyranyl) phosphorothiolothionate This compound was prepared from diisopropyl phosphorothiolothionate (0.1 mole) and 2-methoxy-5-methyl- 3,4-dihydro-2H-pyr-an (0.1 mole) according to the procedure of Example 1.

EXAMPLE 6 0,0-diisobutyl S-(6-meth0xytetrahydro-2-pyranyl) phosphorothiolothionate [(CH3)2CHCH2O]2P (S) S 00133 This compound was prepared from diisobutyl phosphorothiolothionate (0.1 mole) and 2-methoxy-3,4-dihydro-2H-pyran according to the procedure of Example 1.

EXAMPLE 7 O-ethyl O-methyl S-(6-ethoxytetrahydr0-2-pyranyl) phosphorothiolothionate This light yellow oil was prepared from O-ethyl 0- methyl phosphorothiolothionate (0.1 mole) and Z-ethoxy- 3,4'dihydro-2H-pyran (0.1 mole) according to the procedure of Example 1, 11 1.5186.

EXAMPLE 8 O-ethyl O-propyl S-(tetrahydr0-6-meth0xy-4-methyl-2- pyranyl) phosphorothiolothionate CHQO CzHsO This compound was prepared from O-ethyl O-methyl phosphorothiolothionate (0.1 mole) and 2-methoxy-4- methyl-3,4-dihydro-2I-I-pyran (0.1 mole) according to the procedure of Example 1, n 1.5000.

EXAMPLE 1() 0,0-dimethyl S-(6-eth0xytetrahydro-Z-pyranyl) phosphorothiolothionate This light yellow oily product was prepared from dimethyl phosphorothiolothionate (0.1 mole) and Z-ethoxy- 3,4-di-hydro-2H-pyran (0.1 mole) according to the pro cedure of Example 1, n 1.5332.

EXAMPLE 1 1 Use of compounds as insecticides.Tests against mites were carried out in the following manner. Acetone solutions containing 1% of the candidate compounds were prepared and diluted with water to give solutions of the desired concentration for testing. Two heavily infested bean leaves containing adult two-spotted mites (Tetranychus bimaculalus Harvey) were carefully dipped in the above solutions and dried in a gentle air stream. The leaves were placed on damp paper toweling in Petri dishes and observed after 24 hours for mortality among the adult mites.

It should be noted that tests using acetone-water solutions (containing none of the toxicant) kill none of the mites.

The products of Examples 3 to 10 produce results comparable to the products of Examples 1 and 2.

The unexpectedly high toxicity of the compounds of the invention against mites and aphids is apparent from the data in the above table. Compounds 1 and 2 are highly toxic to mites and aphids even at low concentrations while compound 3 is only slightly toxic to mites and inelfective against aphids. To be effective insecticides the percent kill at a concentration of 100 ppm. should be at least Compound 3 differs from the products of this invention only in the absence of an alkoxy group on the heterocyclic ring and normally such a slight difference in chemical compounds is not expected to produce such an outstanding difference in toxicity against certain insects.

We claim:

1. Organophosphorus compounds having the structural formula:

wherein R and R are lower alkyl radicals and R R R and R are selected from the group consisting of hydrogen and lower alkyl radicals.

2. 0,0-diethy1 S-(6-ethoxytetrahydro-2-pyranyl) ph References Cited in the file of this patent phorothiolothionate- UNITED STATES PATENTS 3. 0,0-di6thYl S-(t etrahdr0 6 -meth0Xy-4-methyl-2- 2 725 327 Diveley Nov. 29 1955 p pfiwsphorothwlothwnate- 5 2,766,171 Diveley Oct. 9, 1956 4. 0,0-d1ethyl S-(6:etho7ey-4,5,S-tnmethyltetrahydro-Z- FOREIGN PATENTS pyranyl) phosphorothlolothlonate.

5. 0,0-dimethyl S-(6-eth0xy-5,5-dimethy1tetrahydro-2- 739128 Great Bmam 1955 pyranyl) phosphorothiolothionate. OTHER REFERENCES 6. O-ethyl O-methyl S-(tetrahydro-6-mefhoxy-4-meth- 10 Frear et al.: I. of Econ. Ent., v01. 40, pp. 736-741 yl-2-pyranyl) phosphorothiolothionate. 

1. ORGANOPHOSPHORUS COMPOUNDS HAVING THE STRUCTURAL FORMULA: 